Rigid rod aromatic benzthiazole/oxazole heterocyclic polymer

ABSTRACT

There are provided aromatic heterocyclic polymers having repeating units of the formula ##STR1## wherein R 1  is --H or  R 2  is ##STR2## R 3  is ##STR3## and R 4  is R 2  or ##STR4## and B is ##STR5## wherein X is --S--, --O--, or --NH--.

RIGHTS OF THE GOVERNMENT

The invention described herein may be manufactured and used by or forthe Government of the United States for all governmental purposeswithout the payment of any royalty.

This is a division of application Ser. No. 227,977, filed July 29, 1988,now U.S. Pat. No. 4,900,805.

BACKGROUND OF THE INVENTION

This invention relates to high molecular weight benzobisazole polymerscontaining pendent benzthiazole groups.

In general, the class of aromatic heterocyclic extended chain polymersare well known for their outstanding thermal, physical and chemicalproperties. These polymers generally exhibit excellent modulus andtenacity properties, but lack good properties when in compression whichlimits their use as reinforcing structural fibers.

It is an object of the present invention to provide aromaticheterocyclic polymers which exhibit improved compressive properties

Other objects, aspects and advantages of the present invention will beapparent to those skilled in the art from a reading of the followingdetailed disclosure of the invention.

SUMMARY OF THE INVENTION

In accordance with the present invention there are provided polymershaving repeating units of the formula ##STR6## wherein R₁ is --H or##STR7## R₂ is R₃ is ##STR8## and R₄ is R₂ or ##STR9## and B is##STR10## wherein X is --S--, --O-- or --NH--.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polymers of this invention are prepared by the polycondensation of4,6-diaminoresorcinol dihydrochloride, 2,5-diaminohydroquinonedihydrochloride, 4,6-diamino-1,3-benzenedlthiol dihydrochloride,2,5-diamino-1,4-benzenedithiol dihydrochloride or1,2,4,5-tetraaminobenzene tetrahydrochloride and aphenylbenzthiazole-substituted p-terphenylene dicarboxylic acid of theformula ##STR11## wherein R₁ is --H or ##STR12## R₂ is ##STR13## R₃ is##STR14## and R₄ is R₂ or ##STR15##

Preparation of the phenylbenzthiazole-substituted p-terphenylenedicarboxylic acid is described in our co-pending application Ser. No.227,978, filed July 29, 1988, now U.S. Pat. No. 4,892,953.

In conducting the process, the amino hydrochloride monomer may be mixedwith polyphosphoric acid (PPA) then heated, under vacuum or an inert gasatmosphere to about 70° to 130° C. over a period of about 3 to 24 hours,do dehydrochlorinate the amino monomer. At the end of this period, thedicarboxylic acid is added. An additional amount of phosphorouspentoxide and/or PPA may be added as required to provide a stirrablemixture. Alternatively, the amino hydrochloride and dicarboxylic acidmonomers may be mixed with polyphosphoric acid then heated, under vacuumor an inert gas atmosphere to about 70° to 130° C. over a period ofabout 3 to 24 hours, do dehydrochlorinate the amino monomer. Equimolaramounts of the amino and dicarboxylic acid monomers are generally used.The amount of PPA used is that which is sufficient to provide astirrable mixture. In general, the concentration of monomers in the acidranges from about 0.5 to 12.0 percent.

Following dehydrochlorination, the reaction mixture is heated at atemperature in the range of about 75° to 225° C. for a period rangingfrom 24 to 96 hours. Preferably the polymerization is carried out instages, i.e. a step-wise heating schedule is employed. Step-wise heatingis preferred because immediately exposing the reaction mixture torelatively high polymerization temperatures may cause decomposition ofthe monomers. The selection of a particular step-wise heating scheduleis obvious to one of ordinary skill in the art. At the end of thereaction period, the polymer solution is in a very viscous or semi-solidstate. After cooling, the product is washed repeatedly with water whilestirring, after which it is dried under a high vacuum at an elevatedtemperature

The molecular weight of these polymers is commonly indicated by theinherent viscosity of the polymer. The inherent viscosity is commonlydetermined at a concentration of 0.2 weight/volume percent inmethanesulfonic acid at 30° C.

The polymers produced in accordance with the process of the presentinvention may be used to produce fibers and sheets. In order to formthese polymers into fibers or sheets, dopes are prepared containingabout 5 to 15 weight percent of the polymer in a strong acid, such asulfuric acid, methanesulfonic acid, chlorosulfuric acid, and the like,including mixtures thereof. Such dopes may be spun or extruded into acoagulation bath comprising water or a water/methanesulfonic acidmixture.

The following examples illustrate the invention:

EXAMPLE I

The monomers 4,4"-dicarboxy-2'5'-diphenyl-3',6'-[2-(4-phenylbenzthiazole)]-p-terphenyl (0.8892 g, 1.0mmol) and 2,5-diamino-1,4-benzenedithiol dihydrochloride (0.2452 g, 1.0mmol) were placed in 97 g PPA (84% P₂ O₅). Under a nitrogen atmosphere,the mixture was heated slowly to 90° C. to effect dehydrochlorinationand then heated as follows: 105° C. for 2 h; 150° C. for 19 H; and 190°C. for 24 h. The polymer was precipitated into water, washed withammonium hydroxide, methanol and hexane. The air-dried polymer wasfurther dried under reduced pressure (0.02 mm) at 100° C. for 16 h. Anintrinsic viscosity of 12 dL/g was measured in methanesulfonic acid at30° C.

Analysis Calcd. for C₆₄ H₃₆ N₄ S₄ : C, 77 70; H, 3.67; N, 5.66. Found C,75.88; H, 3.75; N, 5.52.

EXAMPLE II

The monomers4,4"-dicarboxy-2'-phenyl-3',6'-[2-(4-phenoxyphenyl)benzthiazole]-p-terphenyl(0.4524 g, 0.5 mmol) and 2,5-diamino-1,4-benzenedithiol dihydrochloride(0.1225 g, 0.5 mmol) were placed in 198 g PPA (84% P₂ O₅). Under anitrogen atmosphere, the mixture was heated slowly to 65° C. to effectdehydrochlorination and then heated as follows: 70° C. for 4 h, 150° C.for 24 h, and 175° C. for 1 h. The polymer was precipitated into water,washed with concentrated ammonium hydroxide, washed with water,methanol, methanol/benzene mixtures, and finally with benzene. Theswollen polymer was then frozen and dried under reduced (0.02 mm)pressure to give 0.37 g (93.5%) of polymer: [η]=11.7 dL/g inmethanesulfonic acid at 30° C.

Analysis Calcd. for C₆₄ H₃₆ N₂ S₄ O: C, 76.46; H, 3.61; N, 5.57. Found:C, 74.52; H, 3.54; N, 5.00.

EXAMPLE III

A mixture of4,4"-dicaroxy-2'-phenyl-3',6'-[2-(4-phenylbenzthiazole)]-p-terphenyl(3.2517 g. 4.0 mmol) 2,5-diamino-1,4-benzenedithio dihydrochloride(0.9802 g 4.0 mmol), and 24.98 g, PPA (77 percent P₂ O₅) was placed in aresin flask equipped with a high torque mechanical stirrer,nitrogen/outlet, and a pressure regulator. Under a nitrogen flow, theflask was evacuated by means of a water aspirator pump. The monomerswere incorporated into the PPA by stirring, and the resulting mixturewas then dehydrochlorinated under reduced pressure (600 mm) by heatingas follows: 25° C./4 hours; 60° C./h: 85° C./2 hours. To this mixturewas added, under a nitrogen atmosphere 10.45 g of P₂ O₅. The mixture washeated as additional 56 hours/85° C. The polymer was precipitated intowater, washed repeatedly with water, methanol and dried under reducedprssure (0.02 mm) at 138° C. An intrinsic viscosity of 23.0 dL/g wasmeasured in methanesulfonic acid at 30° C.

Analysis Calcd. for C₅₈ H₃₂ N₄ S₄ : C, 76.28; H, 3.53; N, 6.14. Found:C, 75.30; H, 3.15; N, 5.40.

EXAMPLE IV

The monomers4,4"-dicarboxy-2',5'-diphenyl-3',6'-[2-(4-phenylbenzthiazole)]-p-terphenyl(0.4445 g, k0.5 mmol) and 4,5-diamino-1,3-benzenediol dihydrochloride(0.1065 g, 0.5 mmol) were placed in 100 g PPA (84% P₂ O₅). Under anitrogen atmosphere, the mixture was heated to 60° C. to effectdehydrochlorination (16 h) and then heated as follows 100° C. for 5 h,150° C. for 16 h, 175° C. for 8 h, 180° C. for 16 h, and 190° C. for 2h. The polymer was precipitated into water, washed with ammoniumhydroxide, water, and methanol. The air-dried polymer was further driedunder reduced pressure (0.02 mm) at 100° C. for 16 h. An intrinsicviscosity of 7.7 dL/g was measured in methanesulfonic acid at 30° C.

Analysis Calcd. for C₆₄ H₃₆ N₄ S₂ O₂ :

C, 80.31; H, 3.79; N, 5.85.

C Found: C. 74.99; H, 3.76; N, 5.67.

EXAMPLE V

The monomers4,4"-dicarboxy-2'-phenyl-3',6'-[2-4-phenoxyphenyl)benzthiazole]-p-terphenyl(o.4528 g, 0.5 mmol) and 4,6-diamino-1,3-benzenediol dihydrochloride (01066 g, 0.5 mmol) were placed in 198 g PPA (84% P₂ O₅). The temperaturewas raised to 75° C. under a nitrogen atmosphere to effectdehydrochlorination of the amino monomer and then heated as follows:150° C./18 h; 180° C./6.5 h. The polymer was precipitated into water,washed with concentrated ammonium hydroxide, water, and methanol. Theair-dried polymer was further dried under reduced pressure (0.02 mm) at100° C. for 16 h. An intrinsic viscosity of 8.44 dL/g was measured inmethanesulfonic acid at 30° C.

Analysis Calcd. for C₆₄ H₃₆ N₄ S₂ O₃ : C, 78.99; H, 3.73; N, 5.76.Found: C, 75.75; H, 3.79; N, 5.36.

Various modifications of the present invention can be made in view ofthe foregoing disclosure without departing from the spirit and scope ofthe invention.

We claim:
 1. An aromatic heterocyclic polymer having repeating units ofthe formula ##STR16## wherein R₁ is --H or ##STR17## R₂ is ##STR18## R₃is ##STR19## and R₄ is R₂ or ##STR20## and B is ##STR21## wherein X is--O--.
 2. The polymer of claim 1 wherein B is ##STR22##
 3. The polymerof claim 2 wherein R₁ is --H and R₄ is R₂.
 4. The polymer of claim 2wherein R₁ is --H and R₄ is ##STR23##
 5. The polymer of claim 2 whereinR₁ is ##STR24## and R₄ is R₂.
 6. The polymer of claim 2 wherein R₁ is##STR25## and R₄ is ##STR26##
 7. The polymer of claim 1 wherein B is##STR27##
 8. The polymer of claim 7 wherein R₁ is --H and R₄ is R₂. 9.The polymer of claim 7 wherein R₁ is --H and R₄ is ##STR28##
 10. Thepolymer of claim 7 wherein R₁ is ##STR29## and R₄ is R₂.
 11. The polymerof claim 7 wherein R₁ is ##STR30## and R₄ is ##STR31##